Lennox SL280DFV User Manual
INSTALLATION
2011 Lennox Industries Inc.
Dallas, Texas, USA
DOWNFLOW
INSTRUCTIONS
SL280DFV
DAVE LENNOX SIGNATURE
COLLECTION GAS FURNACE
DOWNFLOW AIR DISCHARGE
506710−01
06/2011
Supersedes 01/2011
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, personal injury or loss of life. Installation and service must
be performed by a licensed professional installer (or
equivalent), service agency or the gas supplier.
®
Litho U.S.A.
AIR FLOW
CAUTION
As with any mechanical equipment, personal injury
can result from contact with sharp sheet metal
edges. Be careful when you handle this equipment.
This is a safety alert symbol and should never be ignored.
When you see this symbol on labels or in manuals, be alert
to the potential for personal injury or death.
Table of Contents
Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts Arrangement 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SL280DFV Gas Furnace 4. . . . . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List 4. . . . . . . . . . . . . . . . . . . . . . . .
Safety Information 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Use of Furnace as a Construction Heater 5. . . . . . . . . . .
General 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion, Dilution & Ventilation Air 6. . . . . . . . . . . . . .
Setting Equipment 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filters 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Duct System 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Venting 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Piping 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
06/11
*2P0611*
Page 1
NOTICE
A thermostat is not included and must be ordered
separately.
The Lennox icomfort Touch thermostat must be
used in communicating applications.
In non−communicating applications, the Lennox
ComfortSense
well as other non−communicating thermostats.
In all cases, setup is critical to ensure proper system operation.
Field wiring for both communicating and non−communicating applications is illustrated in diagrams,
which begin on Page 23.
Electrical 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Integrated Control Settings 32. . . . . . . . . . . . . . . . . . . . . . .
Blower Performance Data 35. . . . . . . . . . . . . . . . . . . . . . . .
Unit Start−Up 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Pressure Adjustment 40. . . . . . . . . . . . . . . . . . . . . . . .
Proper Combustion 40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Altitude 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other Unit Adjustments 42. . . . . . . . . . . . . . . . . . . . . . . . . .
Heating Sequence of Operation 42. . . . . . . . . . . . . . . . . . .
Service 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Planned Service 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair Parts List 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Integrated Control Diagnostic Codes 48. . . . . . . . . . . . . . .
Program Unit Capacity/Size Mode 55. . . . . . . . . . . . . . . . .
Troubleshooting 56. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
®
7000 thermostat may be used, as
506710−01
*P506710-01*
Unit Dimensions − inches (mm)
3−1/8
(79)
9/16
(14)
D
RETURN AIR
OPENING
B
FLUE OUTLET
(Top)
19−7/16
9/16
(14)
(494)
9/16
(14)
TOP VIEW
A
B
9/16
(14)
1−1/2 (38)
Front Panel
27−3/4
(7705)
19−7/16
(494)
9/16
(14)
ELECTRICAL INLET
(Either Side)
GAS PIPING INLET
(Either Side)
19−1/4
Supply
(489)
Air
C
Supply
Air
33
(838)
5−3/8 (137) Right
2−1/8 (54) Left
6−5/8 (168) Right
7−1/8 (181) Left
3/4
(19)
FRONT VIEW SIDE VIEW
Model No.
SL280DF070V36A 14−1/2 368 13−3/8 340 13 330 4−3/4 121
SL280DF090V48B
SL280DF090V60C
SL280DF110V60C
17−1/2 446 16−3/8 416 16 406 6−1/4 159
A B C D
in. mm in. mm in. mm in. mm
21 533 19−7/8 504 19−1/2 495 8 203
Page 2
Parts Arrangement
CONTROL BOX
(Includes two−stage integrated control,
transformer and circuit breaker)
INTERNAL FLUE
PIPE ASSEMBLY
GASKET
FLUE CHASE
BLOWER ASSEMBLY
SECONDARY LIMIT
DOOR INTERLOCK SWITCH
ROLLOUT SWITCH
INNER BLOWER ACCESS PANEL
ACCESS PANEL
PRIMARY LIMIT LOCATION
HEAT EXCHANGER
COMBUSTION AIR INDUCER
PRESSURE SWITCHES
COMBUSTION AIR INDUCER
GAS VALVE
BURNER BOX ASSEMBLY
FIGURE 1
Page 3
SL280DFV Gas Furnace
The SL280DFV gas furnace is equipped with a two−stage,
variable speed integrated control. the control is compatible with:
Communicating thermostats − icomfort Touch
Non−communicating thermostats − ComfortSense or other conventional thermostats.
Control systems − Harmony III Zone Control System
(non−communicating). Each SL280DFV unit is shipped
ready for installation in the downflow position.
®
.
Shipping and Packing List
Package 1 of 1 contains
1 − Assembled SL280DFV unit
1 − Bag assembly containing the following:
2 − Screws
1 − Snap bushing
1 − Snap plug
1 − Wire tie
1 − Vent warning label
1 − Owner’s manual and warranty card
The following items may be ordered separately:
1 − Thermostat
1 − Propane/LP changeover kit
1 − Combustible flooring base
Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.
Safety Information
DANGER
Danger of explosion.
There are circumstances in which odorant used with
LP/propane gas can lose its scent. In case of a leak,
LP/propane gas will settle close to the floor and may
be difficult to smell. An LP/propane leak detector
should be installed in all LP applications.
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, personal injury or loss of life. Installation and service must
be performed by a licensed professional installer (or
equivalent), service agency or the gas supplier.
CAUTION
As with any mechanical equipment, personal injury
can result from contact with sharp sheet metal
edges. Be careful when you handle this equipment.
Certifications
SL280DFV units are CSA International certified.
In the USA, installation of gas furnaces must conform with
local building codes. In the absence of local codes, units
must be installed according to the current National Fuel
Gas Code (ANSI-Z223.1). The National Fuel Gas Code is
available from the following address:
American National Standards Institute, Inc.
11 West 42nd Street
New York, NY 10036
Clearances
Adequate clearance must be made around the air openings into the vestibule area. In order to ensure proper unit
operation, combustion and ventilation air supply must be
provided according to the current National Fuel Gas Code.
Vent installations must be consistent with the venting
tables (in this instruction) and applicable provisions of local
building codes.
This furnace is CSA International certified for installation
clearances to combustible material as listed on the unit
nameplate and in the tables in figure 13. Accessibility and
service clearances must take precedence over fire protection
clearances.
Installed Locations
For installation in a residential garage, the furnace must
be installed so that the burner(s) and the ignition source
are located no less than 18 inches (457 mm) above the
floor. The furnace must be located or protected to avoid
physical damage by vehicles. When a furnace is installed
in a public garage, hangar, or other building that has a hazardous atmosphere, the furnace must be installed according to recommended good practice requirements and current National Fuel Gas Code.
NOTE − Furnace must be adjusted to obtain a temperature
rise (high and low fire) within the range(s) specified on the unit
nameplate. Failure to do so may cause erratic limit operation
and may also result in premature heat exchanger failure.
This SL280DFV furnace must be installed so that its electrical components are protected from water.
Installed in Combination with a Cooling Coil
When this furnace is used with cooling units, it shall be
installed in parallel with, or on the upstream side of, cooling
units to avoid condensation in the heating compartment.
With a parallel flow arrangement, a damper (or other
means to control the flow of air) must adequately prevent
Page 4
chilled air from entering the furnace (see figure 1). If the
damper is manually operated, it must be equipped to prevent operation of either the heating or the cooling unit, unless it is in the full HEAT or COOL setting.
GAS UNIT
Dampers
(open during heating
operation only)
AIR HANDLER
Dampers
(open during cooling
operation only)
FIGURE 1
When installed, this furnace must be electrically grounded
according to local codes. In addition, in the United States,
installation must conform with the current National Electric Code, ANSI/NFPA No. 70. The National Electric Code
(ANSI/NFPA No. 70) is available from the following address:
National Fire Protection Association
1 Battery March Park
Quincy, MA 02269
NOTE − This furnace is designed for a minimum continuous return air temperature of 60°F (16°C) or an intermittent operation down to 55°F (13°C) dry bulb for cases
where a night setback thermostat is used. Return air temperature must not exceed 85°F (29°C) dry bulb.
The SL280DFV furnace may be installed in alcoves, closets, attics, basements, garages, and utility rooms in the
downflow position.
This furnace design has not been CSA International certified for installation in mobile homes, recreational vehicles,
or outdoors.
Use of Furnace as Construction Heater
Lennox does not recommend the use of SL280DFV units
as a construction heater during any phase of construction.
Very low return air temperatures, harmful vapors and operation of the unit with clogged or misplaced filters will damage the unit.
SL280DFV units may be used for heating of buildings or
structures under construction, if the following conditions
are met:
D The vent system must be permanently installed per
these installation instructions.
D A room thermostat must control the furnace. The use of
fixed jumpers that will provide continuous heating is not
allowed.
D The return air duct must be provided and sealed to the
furnace.
D Return air temperature range between 60°F (16°C) and
80°F (27°C) must be maintained.
D Air filters must be installed in the system and must be
maintained during construction.
D Air filters must be replaced upon construction comple-
tion.
D The input rate and temperature rise must be set per the
furnace rating plate.
D One hundred percent (100%) outdoor air must be pro-
vided for combustion air requirements during construction. Temporary ducting may supply outdoor air to the
furnace. Do not connect duct directly to the furnace.
Size the temporary duct following these instructions in
section for Combustion, Dilution and Ventilation Air in a
confined space with air from outside.
D The furnace heat exchanger, components, duct system,
air filters and evaporator coils must be thoroughly
cleaned following final construction clean−up.
D All furnace operating conditions (including ignition, in-
put rate, temperature rise and venting) must be verified
according to these installation instructions.
General
These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.
In addition to the requirements outlined previously, the following general recommendations must be considered
when installing a SL280DFV furnace:
Place the furnace as close to the center of the air dis-
tribution system as possible. The furnace should also be
located close to the chimney or vent termination point.
Do not install the furnace where drafts might blow direct-
ly into it. This could cause improper combustion and unsafe operation.
Do not block the furnace combustion air openings with
clothing, boxes, doors, etc. Air is needed for proper
combustion and safe unit operation.
When the furnace is installed in an attic or other insu-
lated space, keep insulation away from the furnace.
NOTE − The Commonwealth of Massachusetts stipulates these additional requirements:
D Gas furnaces shall be installed by a licensed plumb-
er or fitter only.
Page 5
D The gas cock must be T handle" type.
D When a furnace is installed in an attic, the passage-
way to and service area surrounding the equipment
shall be floored.
WARNING
Product contains fiberglass wool.
Disturbing the insulation in this product during
installation, maintenance, or repair will expose you
to fiberglass wool. Breathing this may cause lung
cancer. (Fiberglass wool is known to the State of California to cause cancer.)
Fiberglass wool may also cause respiratory, skin,
and eye irritation.
To reduce exposure to this substance or for further
information, consult material safety data sheets
available from address shown below, or contact your
supervisor.
Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379−9900
Combustion, Dilution & Ventilation Air
In the past, there was no problem in bringing in sufficient outdoor air for combustion. Infiltration provided all the air that
was needed. In today’s homes, tight construction practices
make it necessary to bring in air from outside for combustion. Take into account that exhaust fans, appliance vents,
chimneys, and fireplaces force additional air that could be
used for combustion out of the house. Unless outside air is
brought into the house for combustion, negative pressure
(outside pressure is greater than inside pressure) will build
to the point that a downdraft can occur in the furnace vent
pipe or chimney. As a result, combustion gases enter the living space creating a potentially dangerous situation.
In the absence of local codes concerning air for combustion and ventilation, use the guidelines and procedures in
this section to install SL280DFV furnaces to ensure efficient and safe operation. You must consider combustion air
needs and requirements for exhaust vents. A portion of this
information has been reprinted with permission from the
National Fuel Gas Code (ANSI-Z223.1). This reprinted material is not the complete and official position of the ANSI on
the referenced subject, which is represented only by the
standard in its entirety.
CAUTION
Do not install the furnace in a corrosive or contaminated atmosphere. Meet all combustion and ventilation air requirements, as well as all local codes.
CAUTION
Insufficient combustion air can cause headaches,
nausea, dizziness or asphyxiation. It will also cause
excess water in the heat exchanger resulting in rusting and premature heat exchanger failure. Excessive
exposure to contaminated combustion air will result
in safety and performance related problems. Avoid
exposure to the following substances in the combustion air supply:
Permanent wave solutions
Chlorinated waxes and cleaners
Chlorine base swimming pool chemicals
Water softening chemicals
De-icing salts or chemicals
Carbon tetrachloride
Halogen type refrigerants
Cleaning solvents (such as perchloroethylene)
Printing inks, paint removers, varnishes, etc.
Hydrochloric acid
Cements and glues
Antistatic fabric softeners for clothes dryers
Masonry acid washing materials
All gas-fired appliances require air for the combustion process. If sufficient combustion air is not available, the furnace or other appliances will operate inefficiently and unsafely. Enough air must be provided to meet the needs of all
fuel-burning appliances and appliances such as exhaust
fans which force air out of the house. When fireplaces, exhaust fans, or clothes dryers are used at the same time as
the furnace, much more air is necessary to ensure proper
combustion and to prevent a downdraft. Insufficient air
causes incomplete combustion which can result in carbon
monoxide.
In addition to providing combustion air, fresh outdoor air
dilutes contaminants in the indoor air. These contaminants may include bleaches, adhesives, detergents, solvents and other contaminants which can corrode furnace
components.
The requirements for providing air for combustion and ventilation depend largely on whether the furnace is installed in
an unconfined or a confined space.
Unconfined Space
An unconfined space is an area such as a basement or
large equipment room with a volume greater than 50 cubic
feet (1.42 m
bined input rating of all appliances installed in that space.
This space also includes adjacent rooms which are not
separated by a door. Though an area may appear to be unconfined, it might be necessary to bring in outdoor air for
combustion if the structure does not provide enough air by
infiltration. If the furnace is located in a building of tight
construction with weather stripping and caulking around
the windows and doors, follow the procedures in the air
from outside section.
3
) per 1,000 Btu (.29 kW) per hour of the com-
Page 6
Confined Space
A confined space is an area with a volume less than 50 cubic feet (1.42 m
3
) per 1,000 Btu (.29 kW) per hour of the
combined input rating of all appliances installed in that
space. This definition includes furnace closets or small
equipment rooms.
When the furnace is installed so that supply ducts carry air
circulated by the furnace to areas outside the space containing the furnace, the return air must be handled by ducts
which are sealed to the furnace casing and which terminate
outside the space containing the furnace. This is especially
important when the furnace is mounted on a platform in a
confined space such as a closet or small equipment room.
Even a small leak around the base of the unit at the platform
or at the return air duct connection can cause a potentially
dangerous negative pressure condition. Air for combustion
and ventilation can be brought into the confined space either
from inside the building or from outside.
EQUIPMENT IN CONFINED
CHIMNEY
OR GAS
VENT
FURNACE
NOTE − Each opening shall have a free area of at least one square
inch (645 mm
ing of all equipment in the enclosure, but not less than 100 square
inches (64516 mm
2
) per 1,000 Btu (.29 kW) per hour of the total input rat-
2
).
SPACE ALL AIR FROM INSIDE
WATER
HEATER
OPENINGS
(To Adjacent
Room)
FIGURE 2
Air from Inside
If the confined space that houses the furnace adjoins a
space categorized as unconfined, air can be brought in by
providing two permanent openings between the two
spaces. Each opening must have a minimum free area of 1
square inch (645 mm
2
) per 1,000 Btu (.29 kW) per hour of
total input rating of all gas−fired equipment in the confined
space. Each opening must be at least 100 square inches
(64516 mm
2
). One opening shall be within 12 inches (305
mm) of the top of the enclosure and one opening within 12
inches (305 mm) of the bottom. See figure 2.
Air from Outside
If air from outside is brought in for combustion and ventilation, the confined space must have two permanent openings. One opening shall be within 12 inches (305 mm) of the
top of the enclosure and one opening within 12 inches (305
mm) of the bottom. These openings must communicate directly or by ducts with the outdoors or spaces (crawl or attic) that freely communicate with the outdoors or indirectly
through vertical ducts. Each opening shall have a minimum
free area of 1 square inch (645 mm
2
) per 4,000 Btu (1.17
kW) per hour of total input rating of all equipment in the enclosure. See figures 3 and 4. When communicating with
the outdoors through horizontal ducts, each opening shall
have a minimum free area of 1 square inch (645 mm
2
) per
2,000 Btu (.56 kW) per total input rating of all equipment in
the enclosure. See figure 5.
When ducts are used, they shall be of the same cross−sectional area as the free area of the openings to which they
connect. The minimum dimension of rectangular air ducts
shall be no less than 3 inches (75 mm). In calculating free
area, the blocking effect of louvers, grilles, or screens must
be considered. If the design and free area of protective covering is not known for calculating the size opening required,
it may be assumed that wood louvers will have 20 to 25 percent free area and metal louvers and grilles will have 60 to
75 percent free area. Louvers and grilles must be fixed in the
open position or interlocked with the equipment so that they
are opened automatically during equipment operation.
Page 7
CHIMNEY OR
GAS VENT
FURNACE
(Inlet Air from Crawlspace and Outlet Air to Ventilated Attic)
VENTILATION LOUVERS
(Each end of attic)
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
OUTLET
AIR
WATER
HEATER
CHIMNEY
OR GAS
VENT
FURNACE
VENTILATION
LOUVERS
(For unheated crawl space)
NOTE−The inlet and outlet air openings shall each have a free area of at least one square inch (645
2
mm
) per 4,000 Btu (1.17 kW) per hour of the total input rating of all equipment in the enclosure.
INLET
AIR
FIGURE 3
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
(All Air Through Ventilated Attic)
VENTILATION LOUVERS
(Each end of attic)
OUTLET
AIR
INLET AIR
(Ends 12 in.
above bottom)
FURNACE
CHIMNEY
OR GAS
VENT
CONFINED SPACE
WATER
HEATER
OUTLET AIR
INLET AIR
EQUIPMENT IN
ALL AIR FROM
OUTSIDE
WATER
HEATER
NOTE−The inlet and outlet air openings shall each have a
free area of at least one square inch (645 mm
2
) per 4,000
Btu (1.17 kW) per hour of the total input rating of all equipment in the enclosure.
FIGURE 4
Page 8
NOTE − Each air duct opening shall have a free area of at least
one square inch (645 mm
2
) per 2,000 Btu (.59 kW) per hour of
the total input rating of all equipment in the enclosure. If the
equipment room is located against an outside wall and the air
openings communicate directly with the outdoors, each opening shall have a free area of at least one square inch (645 mm
per 4,000 Btu (1.17 kW) per hour of the total input rating of all
other equipment in the enclosure.
FIGURE 5
2
)
Downflow Installation
Downflow unit installs in three ways: on non−combustible
flooring, on combustible flooring using a downflow combustible flooring base, or on a reverse−flow cooling cabinet.
Do not drag the unit across the floor.
Installation on Non−Combustible Flooring (Figure 6)
CAUTION
The furnace and downflow combustible flooring
base shall not be installed directly on carpeting, tile,
or other combustible material other than wood flooring.
1 − Cut floor opening keeping in mind clearances listed on
unit rating plate. Also keep in mind gas supply connections, electrical supply, flue and air intake connections
and sufficient installation and servicing clearances.
See table 1 for correct floor opening size.
2 − Flange warm air plenum and lower the plenum into the
opening.
3 − Set the unit over the plenum and seal the plenum to
the unit.
4 − Ensure that the seal is adequate.
SL280DFV UNIT
OPENING
SUPPLY AIR
PLENUM
SL280DFV UNIT
SUPPLY AIR PLENUM
PROPERLY
SIZED FLOOR
OPENING
DOWNFLOW
COMBUSTIBLE
FLOORING BASE
FIGURE 7
TABLE 2
COMBUSTIBLE FLOOR OPENING SIZE
Cabinet Width
A (14.5")
B (17.5")
C (21")
NOTE − Floor opening dimensions listed are 1/4 inch (6 mm) larger than
unit opening. See unit dimensions on page 2.
Front to Rear Side to Side
in. mm in. mm
22 559 15−3/4 400
22 559 18−3/4 476
22 559 22−3/4 578
FIGURE 6
TABLE 1
NON−COMBUSTIBLE FLOOR OPENING SIZE
Cabinet Width
A (14.5") 19−3/4 502 13−1/4 337
B (17.5") 19−3/4 502 16−1/4 413
C (21") 19−3/4 502 19−3/4 502
NOTE − Door opening dimensions listed are 1/4 inch (6 mm) larger than
the unit opening. See unit dimensions on page 2.
Front to Rear Side to Side
in. mm in. mm
Installation on Combustible Flooring (Figure 7)
1 − When unit is installed on a combustible floor, a down-
flow combustible flooring base must be installed between the furnace and the floor. The base must be ordered separately.
See table 2 for opening size to cut in floor.
2 − After opening is cut, set combustible flooring base into
opening.
3 − Check sealing strips on combustible flooring base to
make sure they are properly glued and positioned.
4 − Lower supply air plenum into downflow combustible
flooring base until plenum flanges seal against the
strips.
NOTE − Be careful not to damage sealing strips. Check
for a tight seal.
5 − Set the furnace over the plenum.
6 − Ensure that the seal between the furnace and plenum
is adequate.
Installation on Cooling Cabinet (Figure 8)
1 − Refer to reverse−flow coil installation instructions for
correctly sized opening in floor and installation of cabinet.
NOTE − Downflow combustible flooring kit is not used
2 − When cooling cabinet is in place, set and secure the
furnace according to the instructions that are provided
with the cooling coil. Secure the furnace to the cabinet.
3 − Seal the cabinet and check for air leaks.
Page 9
PROPERLY
SIZED FLOOR
OPENING
SL280DFV UNIT
COOLING COIL
PLENUM
Setting Equipment
WARNING
Do not install the furnace on its front, back or in the
horizontal position. See figure 12. Do not connect the
return air ducts to the back of the furnace. Doing so
will adversely affect the operation of the safety control devices, which could result in personal injury or
death.
Install the SL280DFV gas furnace as shipped in the
downflow position only. Do not install the furnace hori-
zontally.
FIGURE 8
Return Air Opening −− Downflow Units
The following steps should be taken when installing plenum:
1 − Bottom edge of plenum should be flanged with a
hemmed edge (See figure 9).
PLENUM
SECURE FROM
OUTSIDE CABINET
Side View
HEMMED EDGE
SEALING STRIP
(Field Provided)
CABINET SIDE PANEL
FIGURE 9
2 − Sealing strip should be used.
3 − In all cases, plenum should be secured to top flanges
of furnace with sheet metal screws.
SECURE FROM IN-
SIDE CABINET
PLENUM
Side View
HEMMED EDGE
Select a location that allows for the required clearances
that are listed on the unit nameplate. Also consider gas
supply connections, electrical supply, vent connection,
and installation and service clearances [24 inches (610
mm) at unit front]. The unit must be level.
NOTE − Units with 1/2 hp blower motors are equipped with
three flexible legs and one rigid leg. See figure 11. The rigid
leg is equipped with a shipping bolt and a flat white plastic
washer (rather than the rubber mounting grommet used
with a flexible mounting leg). The bolt and washer must
be removed before the furnace is placed into operation. After the bolt and washer have been removed, the rig-
id leg will not touch the blower housing.
SL280DFV07036A WITH 1/2 HP
BLOWER MOTOR
RIGID LEG
remove shipping bolt and washer
FIBERGLASS
SEALING STRIP
(Field Provided)
CABINET SIDE
PANEL
FIGURE 10
4 − In closet installations, it may be impossible to install
sheet metal screws from the outside. In this case,
make plenum with a removable front and install
screws from the inside (See figure 10).
5 − Make certain that an adequate seal is made.
FIGURE 11
WARNING
The blower access panel must be securely in place
when the blower and burners are operating. Gas
fumes, which could contain carbon monoxide, can
be drawn into living space resulting in personal injury or death.
Page 10
Front
Back
FIGURE 12
Downflow Application
Allow for clearances to combustible materials as indicated on the unit nameplate. Minimum clearances for
closet or alcove installations are shown in figure 13.
Downflow Application Installation Clearances
Top
Left Side
Bottom
Type of Vent
Connector
Top 1 in. (25 mm) 1 in. (25 mm)
*Front 2−1/4 in. (57 mm)** 2−1/4in. (57 mm)
Back 0 0
Sides 0† 0
Vent 6 in. (152 mm) 1 in. (25 mm)
Floor NC†† NC††
*Front clearance in alcove installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
** 3−1/4 in. if single wall vent pipe is used.
†Left side requires 3 in. if a single wall vent is used on 14 −1/2 in. cabinets, or 2 in. if a single wall vent is used on 17 − 1/2 in. cabinets.
††The furnace may be installed on a combustible wood floor if an
optional additive base is installed between the furnace and the
combustible floor.
Type C Type B1
Right Side
FIGURE 13
Horizontal
WARNING
Improper installation of the furnace can result in personal injury or death. Combustion and flue products
must never be allowed to enter the return air system
or the living space. Use screws and joint tape to seal
the return air system to the furnace.
In platform installations with bottom return air, the
furnace should be sealed airtight to the return air plenum. A door must never be used as a portion of the
return air duct system. The base must provide a
stable support and an airtight seal to the furnace. Allow absolutely no sagging, cracks, gaps, etc.
The return and supply air duct systems must never
be connected to or from other heating devices such
as a fireplace or stove, etc. Fire, explosion, carbon
monoxide poisoning, personal injury and/or property damage could result.
Filters
This unit is not equipped with a filter or rack. A field−provided high−velocity filter is required for the unit to operate
properly. Table 3 lists recommended filter sizes.
A filter must be in place any time the unit is operating.
TABLE 3
Cabinet Width
A (14−1/2") 14 x 25 x 1 (1)
B (17−1/2") 16 x 25 x 1 (1)
C (21") 20 x 25 x 1 (1)
Return Air Filter Size (inches)
Page 11
Duct System
Use industry-approved standards (such as those published by Air Conditioning Contractors of America or American Society of Heating, Refrigerating and Air Conditioning
Engineers) to size and install the supply and return air duct
system. This will result in a quiet and low-static system that
has uniform air distribution.
NOTE − Do not operate the furnace in the heating mode
with an external static pressure that exceeds 0.8 inches
w.c. Higher external static pressures may cause erratic limit operation.
Ensure that you have made a seal between the supply air
plenum and the furnace and between the furnace and the
return air plenum.
Return Air Plenum
Return air must not be drawn from a room where this
furnace, or any other gas−fueled appliance (i.e., water
heater), or carbon monoxide−producing device (i.e.,
wood fireplace) is installed. When return air is drawn
from a room, a negative pressure is created in the room. If
a gas appliance is operating in a room with negative pressure, the flue products can be pulled back down the vent
pipe and into the room. This reverse flow of the flue gas
may result in incomplete combustion and the formation
of carbon monoxide gas. This toxic gas might then be distributed throughout the house by the furnace duct system.
Venting
A 4−inch diameter flue transition is factory-installed on all
models. Modifying or removing the flue transition will
cause the unit to operate unsafely and will void the unit
certification. The vent connector does not require insula-
tion.
The SL280DFV series units are classified as fan−assisted
Category I furnaces when vertically vented according to
the latest edition of National Fuel Gas Code (NFPA 54 /
ANSI Z223.1). A fan−assisted Category I furnace is an appliance equipped with an integral mechanical means to either draw or force combustion products through the combustion chamber and/or heat exchanger.
NOTE − Use these instructions as a guide. They do not supersede local codes. This furnace must be vented according to all local codes, these installation instructions, and the
provided venting tables in these instructions
The venting tables in this manual were extracted from the
National Fuel Gas Code (NFPA 54 / ANSI Z223.1) and are
provided as a guide for proper vent installation. Proper application, termination, construction and location of vents
must conform to local codes having jurisdiction. In the absence of local codes, the NFGC serves as the defining document.
Refer to the tables and the venting information contained in
these instructions to properly size and install the venting
system.
IMPORTANT
Once the venting system is installed, attach the Disconnected Vent" warning sticker to a visible area of
the plenum near the vent pipe. The warning sticker
is provided in the bag assembly. Order kit 66W04 for
additional stickers.
WARNING
Asphyxiation hazard. The exhaust vent for this furnace must be securely connected to the furnace flue
transition at all times.
VENT CONNECTION
FLUE TRANSITION
COLLAR
FIGURE 14
Use self−drilling sheet metal screws or a mechanical fastener to firmly secure the vent pipe to the round collar of the
flue transition. If self−drilling screws are used to attach the
vent pipe, it is recommended that three be used. Drive one
self−drilling screw through the front and one through each
side of the vent pipe and collar. See figure 14.
Masonry chimneys used to vent Category I central furnaces must be either tile-lined or lined with a listed metal
lining system or dedicated gas vent. Unlined masonry
chimneys are prohibited. See figures 15 and 16 for common venting.
“DISCONNECTED VENT”
WARNING
STICKER
Page 12
Common Venting Using Tile−Lined Interior Masonry Chimney and Combined Vent Connector
MINIMUM LENGTH = AS SHORT AS PRACTICAL.
NOTE− Refer to provided venting
tables for installations.
FOR MAXIMUM LENGTH SEE NOTE TO LEFT
OTHER
APPLIANCE
FIGURE 15
Venting Using a Masonry Chimney
The following additional requirements apply when a lined
masonry chimney is used to vent this furnace.
A chimney with one or more sides exposed to the outside of
the structure is considered to be an exterior chimney.
An exterior masonry chimney that is not tile−lined must be
lined with B1 vent or a listed insulated flexible metal vent.
An exterior tile−lined chimney that is sealed and capped
may be lined with a listed uninsulated flexible metal vent.
If the existing chimney will not accommodate a listed metal
liner, either the chimney must be rebuilt to accommodate
one of these liners or an alternate approved venting method must be found.
Insulation for the flexible vent pipe must be an encapsulated fiberglass sleeve recommended by the flexible vent
pipe manufacturer. See figure 16.
Common Venting Using Metal−Lined Masonry Chimney
SEALED
MAX. LENGTH
−− SEE NOTE
5 ft. (1.5 m)
minimum
VENT CONNECTOR
4 in. (102 mm)
minimum
OTHER
APPLIANCE
NOTE 1 − Refer to the provided venting tables for installations.
BELOW.
MIN. LENGTH −− AS
SHORT AS PRACTICAL
FURNACE
EXTERIOR
CHIMNEY WITH
METAL
LINER
PERMANENTLY
SEALED FIREPLACE
OPENING
FIGURE 16
INTERIOR TILE−LINED
MASONRY CHIMNEY
NOTE − the chimney must be properly
sized per provided venting tables or
lined with listed metal lining system.
VENT
CONNECTOR
FURNACE
PERMANENTLY
SEALED FIREPLACE
OPENING
DO NOT insulate the space between the liner and the
chimney wall with puffed mica or any other loose granular insulating material
IMPORTANT
SINGLE appliance venting of a fan-assisted furnace
into a tile-lined masonry chimney (interior or outside
wall) is PROHIBITED. The chimney must first be lined
with either type B1 vent or an insulated single wall
flexible vent lining system which has been sized according to the provided venting tables and the vent
pipe manufacturer’s instructions.
A fan−assisted furnace may be commonly vented into an
existing lined masonry chimney if the following conditions
are met:
The chimney is currently serving at least one drafthood
equipped appliance
The vent connectors and chimney are sized according
to the provided venting tables.
If type B1 double-wall vent is used inside a chimney, no other appliance can be vented into the chimney. The outer wall
of type B1 vent pipe must not be exposed to flue products.
A type B1 vent or masonry chimney liner shall terminate
above the roof surface with a listed cap or a listed roof assembly according to the terms of their respective listings
and the vent manufacturer’s instructions.
When inspection reveals that an existing chimney is not
safe for the intended purpose, it shall be rebuilt to conform
to nationally recognized standards, lined or relined with
suitable materials, or replaced with a gas vent or chimney
suitable for venting SL280DFV series units. The chimney
passageway must be checked periodically to ensure that it
is clear and free of obstructions.
Do not install a manual damper, barometric draft regulator,
or flue restrictor between the furnace and the chimney.
Page 13
Never connect a Category I appliance to a chimney that is
servicing a solid−fuel appliance. If a fireplace chimney flue
is used to vent this appliance, the fireplace opening must
be permanently sealed.
A type B or listed chimney lining system that passes
through an unused masonry chimney flue is not considered
to be exposed to the outdoors.
General Venting Requirements
Vent all SL280DFV furnaces according to these instructions:
1 − Vent diameter recommendations and maximum allow-
able piping runs are found in the provided venting
tables.
2 − In no case should the vent or vent connector diameter
be less than the diameter specified in the provided
venting tables.
3 − The minimum vent capacity determined by the sizing
tables must be less than the low fire input rating and the
maximum vent capacity must be greater than the high
fire input rating.
4 − Single appliance vents − If the vertical vent or tile-lined
chimney has a larger diameter or flow area than the
vent connector, use the vertical vent diameter to determine the minimum vent capacity and the vent
connector diameter to determine the maximum vent
capacity. The flow area of the vertical vent, however,
shall not exceed 7 times the flow area of the listed appliance categorized vent area, drafthood outlet area or
flue collar area unless designed according to approved
engineering methods.
5 − Multiple appliance vents − The flow area of the largest
section of vertical vent or chimney shall not exceed 7
times the smallest listed appliance categorized vent
area, drafthood outlet area or flue collar area unless designed according to approved engineering methods.
6 − The entire length of single wall metal vent connector
shall be readily accessible for inspection, cleaning,
and replacement.
7 − Single appliance venting configurations with zero lat-
eral lengths (tables 5 and 6) are assumed to have no
elbows in the vent system. For all other vent configurations, the vent system is assumed to have two 90° elbows. For each additional 90° elbow or equivalent (for
example two 45° elbows equal one 90° elbow) beyond
two, the maximum capacity listed in the venting table
should be reduced by 10% (0.90 x maximum listed capacity).
8 − The common venting tables (7, 8, 9, and 10) were gen-
erated using a maximum horizontal vent connector
length of 1−1/2 feet (.46 m) for each inch (25 mm) of
connector diameter as follows:
TABLE 4
Connector Diameter
inches (mm)
3 (76) 4−1/2 (1.37)
4 (102) 6 (1.83)
5 (127) 7−1/2 (2.29)
6 (152) 9 (2.74)
7 (178) 10−1/2 (3.20)
Maximum Horizontal
Connector Length feet (m)
9 − If the common vertical vent is offset, the maximum
common vent capacity listed in the common venting
tables should be reduced by 20%, the equivalent of two
90° elbows (0.80 x maximum common vent capacity).
The horizontal length of the offset shall not exceed
1-1/2 feet (.46 m) for each inch (25 mm) of common
vent diameter.
10 − The vent pipe should be as short as possible with the
least number of elbows and angles required to complete the job. Route the vent connector to the vent using the shortest possible route.
11 − A vent connector shall be supported without any dips
or sags and shall slope a minimum of 1/4 inch (6.4 mm)
per linear foot (305 mm) of connector, back toward the
appliance.
12 − Vent connectors shall be firmly attached to the furnace
flue collar by self−drilling screws or other approved
means, except vent connectors of listed type B vent
material which shall be assembled according to the
manufacturer’s instructions. Joints between sections
of single wall connector piping shall be fastened by
screws or other approved means.
13 − When the vent connector used for Category I ap-
pliances must be located in or pass through a crawlspace or other areas which may be cold, that portion of
the vent connector shall be constructed of listed
double-wall type B vent material or material having
equivalent insulation qualities.
14 − All venting pipe passing through floors, walls, and ceil-
ings must be installed with the listed clearance to combustible materials and be fire stopped according to local codes. In absence of local codes, refer to NFGC
(Z223.1).
15 − No portion of the venting system can extend into, or pass
through any circulation air duct or plenum.
16 − Vent connectors serving Category I appliances shall
not be connected to any portion of mechanical draft
systems operating under positive pressure such as
Category III or IV venting systems.
17 − If vent connectors are combined prior to entering the
common vent, the maximum common vent capacity
listed in the common venting tables must be reduced by
10%, the equivalent of one 90° elbow (0.90 x maximum
common vent capacity).
Page 14
18 − The common vent diameter must always be at least as
large as the largest vent connector diameter.
19 − In no case, shall the vent connector be sized more than
two consecutive table size diameters over the size of
the draft hood outlet or flue collar outlet.
20 − Do not install a manual damper, barometric draft regu-
lator or flue restrictor between the furnace and the
21 − When connecting this appliance to an existing dedi-
cated or common venting system, you must inspect the
venting system’s general condition and look for signs
of corrosion. The existing vent pipe size must conform
to these instructions and the provided venting tables. If
the existing venting system does not meet these requirements, it must be resized.
chimney.
TABLE 5
Capacity of Type B Double−Wall Vents with Type B Double−Wall Connectors
Serving a Single Category I Appliance
Vent and Connector Diameter − D (inches)
Height
H
(feet)
6
8
10
15
20
30
NOTE − Single appliance venting configurations with zero lateral lengths are assumed to have no elbows in the vent system. For all other
vent configurations, the vent system is assumed to have two 90° elbows. For each additional 90° elbow or equivalent (for example two 45°
elbows equal one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maximum listed capacity).
Lateral
L
(feet)
0 0 78 0 152 0 251 0 375
2 13 51 18 97 27 157 32 232
4 21 49 30 94 39 153 50 227
6 25 46 36 91 47 149 59 223
0 0 84 0 165 0 276 0 415
2 12 57 16 109 25 178 28 263
5 23 53 32 103 42 171 53 255
8 28 49 39 98 51 164 64 247
0 0 88 0 175 0 295 0 447
2 12 61 17 118 23 194 26 289
5 23 57 32 113 41 187 52 280
10 30 51 41 104 54 176 67 267
0 0 94 0 191 0 327 0 502
2 11 69 15 136 20 226 22 339
5 22 65 30 130 39 219 49 330
10 29 59 40 121 51 206 64 315
15 35 53 48 112 61 195 76 301
0 0 97 0 202 0 349 0 540
2 10 75 14 149 18 250 20 377
5 21 71 29 143 38 242 47 367
10 28 64 38 133 50 229 62 351
15 34 58 46 124 59 217 73 337
20 48 52 55 116 69 206 84 322
0 0 100 0 213 0 374 0 587
2 9 81 13 166 14 283 18 432
5 21 77 28 160 36 275 45 421
10 27 70 37 150 48 262 59 405
15 33 64 44 141 57 249 70 389
20 56 58 53 132 66 237 80 374
30 NR NR 73 113 88 214 104 346
3 Inch 4 Inch 5 Inch 6 Inch
Appliance Input Rating in Thousands of Btu Per Hour
MIN MAX MIN MAX MIN MAX MIN MAX
Page 15
TABLE 6
Capacity of Type B Double−Wall Vents with Single−Wall Metal Connectors
Serving a Single Category I Appliance
Vent and Connector Diameter − D (inches)
Height
H
(feet)
6
8
10
15
20
30
NOTE − Single appliance venting configurations with zero lateral lengths are assumed to have no elbows in the vent system. For all other
vent configurations, the vent system is assumed to have two 90° elbows. For each additional 90° elbow or equivalent (for example two 45°
elbows equal one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maximum listed capacity).
Lateral
L
(feet)
0 38 77 59 151 85 249 126 373
2 39 51 60 96 85 156 123 231
4 NR NR 74 92 102 152 146 225
6 NR NR 83 89 114 147 163 220
0 37 83 58 164 83 273 123 412
2 39 56 59 108 83 176 121 261
5 NR NR 77 102 107 168 151 252
8 NR NR 90 95 122 161 175 243
0 37 87 57 174 82 293 120 444
2 39 61 59 117 82 193 119 287
5 52 56 76 111 105 185 148 277
10 NR NR 97 100 132 171 188 261
0 36 93 56 190 80 325 116 499
2 38 69 57 136 80 225 115 337
5 51 63 75 128 102 216 144 326
10 NR NR 95 116 128 201 182 308
15 NR NR NR NR 158 186 220 290
0 35 96 54 200 78 346 114 537
2 37 74 56 148 78 248 113 375
5 50 68 73 140 100 239 141 363
10 NR NR 93 129 125 223 177 344
15 NR NR NR NR 155 208 216 325
20 NR NR NR NR 186 192 254 306
0 34 99 53 211 76 372 110 584
2 37 80 55 164 76 281 109 429
5 49 74 72 157 98 271 136 417
10 NR NR 91 144 122 255 171 397
15 NR NR 11 5 131 151 239 208 377
20 NR NR NR NR 181 223 246 357
30 NR NR NR NR NR NR NR NR
3 Inch 4 Inch 5 Inch 6 Inch
Appliance Input Rating in Thousands of Btu Per Hour
MIN MAX MIN MAX MIN MAX MIN MAX
Page 16
Vent
Height
H
(feet)
6
8
10
15
20
30
TABLE 7
Vent Connector Capacity
Type B Double−Wall Vents with Type B Double−Wall Connectors
Serving Two or More Category I Appliances
Connector
Rise
R
(feet)
1 22 37 35 66 46 106 58 164
2 23 41 37 75 48 121 60 183
3 24 44 38 81 49 132 62 199
1 22 40 35 72 49 114 64 176
2 23 44 36 80 51 128 66 195
3 24 47 37 87 53 139 67 210
1 22 43 34 78 49 123 65 189
2 23 47 36 86 51 136 67 206
3 24 50 37 92 52 146 69 220
1 21 50 33 89 47 142 64 220
2 22 53 35 96 49 153 66 235
3 24 55 36 102 51 163 68 248
1 21 54 33 99 46 157 62 246
2 22 57 34 105 48 167 64 259
3 23 60 35 110 50 176 66 271
1 20 62 31 113 45 181 60 288
2 21 64 33 118 47 190 62 299
3 22 66 34 123 48 198 64 309
3 Inch 4 Inch 5 Inch 6 Inch
MIN MAX MIN MAX MIN MAX MIN MAX
Vent and Connector Diameter − D (inches)
Appliance Input Rating in Thousands of Btu Per Hour
TABLE 8
Common Vent Capacity
Type B Double−Wall Vents with Type B Double−Wall Connectors
Serving Two or More Category I Appliances
Vent
Height
H
(feet)
6 92 81 140 11 6 204 161 309 248
8 101 90 155 129 224 178 339 275
10 110 97 169 141 243 194 367 299
15 125 112 195 164 283 228 427 352
20 136 123 215 183 314 255 475 394
30 152 138 244 210 361 297 547 459
FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT
4 Inch 5 Inch 6 Inch 7 Inch
Appliance Input Rating in Thousands of Btu Per Hour
Common Vent Diameter − D (inches)
Page 17
Height
H
(feet)
6
8
10
15
20
30
TABLE 9
Vent Connector Capacity
Type B Double−Wall Vents with Single−Wall Metal Connectors
Serving Two or More Category I Appliances
Vent and Connector Diameter − D (inches)
Lateral
L
(feet)
1 NR NR NR NR NR NR NR NR
2 NR NR NR NR NR NR 168 182
3 NR NR NR NR 121 131 175 198
1 NR NR NR NR NR NA NR NR
2 NR NR NR NR 125 126 184 193
3 NR NR NR NR 130 138 191 208
1 NR NR NR NR 119 121 182 186
2 NR NR 84 85 124 134 189 203
3 NR NR 89 91 129 144 197 217
1 NR NR 79 87 116 138 177 214
2 NR NR 83 94 121 150 185 230
3 NR NR 87 100 127 160 193 243
1 49 56 78 97 115 152 175 238
2 52 59 82 103 120 163 182 252
3 55 62 87 107 125 172 190 264
1 47 60 77 110 112 175 169 278
2 51 62 81 115 117 185 177 290
3 54 64 85 119 122 193 185 300
3 Inch 4 Inch 5 Inch 6 Inch
Appliance Input Rating in Thousands of Btu Per Hour
MIN MAX MIN MAX MIN MAX MIN MAX
NOTE − Single appliance venting configurations with zero lateral lengths are assumed to have no elbows in the vent system. For all other
vent configurations, the vent system is assumed to have two 90° elbows. For each additional 90° elbow or equivalent (for example two 45°
elbows equal one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maximum listed capacity).
TABLE 10
Common Vent Capacity
Type B Double−Wall Vents with Single−Wall Metal Connectors
Serving Two or More Category I Appliances
Vent
Height
H
(feet)
6 NA 78 NA 11 3 200 158 304 244
8 NA 87 NA 126 218 173 331 269
10 NA 94 163 137 237 189 357 292
15 121 108 189 159 275 221 416 343
20 131 118 208 177 305 247 463 383
30 145 132 236 202 350 286 533 446
FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT
4 Inch 5 Inch 6 Inch 7 Inch
Appliance Input Rating in Thousands of Btu Per Hour
Common Vent Diameter − D (inches)
Page 18
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